Should I drop this FHA/Rural Development foreclosure on a house?

My sister has been paying on a house for about 27yrs. She moved into supportive living and now the house is going into foreclosure. In July, I paid the house payments up so we could move her belongings (she is a hoarder) into her new home and get her possessions out of the house.
I planned to buy her house, so I started the steps including paying for a very expensive certified appraisal, and trying to figure out what I have to do to get the house. Ive been dealing with an office in St. Louis who told me I had to get an appraisal. I also have been dealing with the local office who asked me why I got an appraisal. Now they want me to hire a lawyer. My sister refuses to send a fax to the rural development office so I can get information on her loan. I hired an attorney, but if she will not give a release of information, I am just out of luck, and this seems to be getting more and more expensive. Should I just forget it and let them foreclose on her house?

Read more: Should I drop this FHA/Rural Development foreclosure on a house?